NEXT TIME you see a fancy new electric car, ask the owner for a ride. After all, you helped pay for it. The federal government provides a $7,500 tax credit for buying or leasing electric vehicles, which means that it transfers that much money from everyone else to the relative handful of Americans who have so far purchased a plug-in vehicle. Cost before tax credit: $74,500 in the case of a Tesla Model S, or $37,495 for a smaller, less capable Chevrolet Bolt. This is a Robin-Hood-in-reverse policy. Electric-car purchasers tend to be upper-income, and the credit is non-refundable — meaning its value increases as your income tax liability increases (up to the $7,500 maximum). It’s worth nothing to lower-income folks who don’t owe federal tax. And even if it were fully refundable, lower-income people would rarely qualify because the cars would still be too expensive for them. Some 90 percent of the credit’s benefits accrue to the top 20 percent of taxpayers, according to a 2015 study by Severin Borenstein and Lucas Davis, economists at the University of California at Berkeley.